Disclosed are intermediate transfer members, and more specifically, coated seamed intermediate transfer members useful in transferring a developed image in an electrostatographic, for example xerographic, including digital, image on image, and the like, printers, machines or apparatuses. In embodiments, there are selected, for example, seamed intermediate transfer members comprised of a conductive material like carbon black, a polyaniline, or mixtures thereof dispersed in a polymer solution, such as a polyamic acid solution to form a polyimide supporting substrate as illustrated in applications U.S. application Ser. No. 12/129,995, U.S. application Ser. No. 12/181,354, and U.S. application Ser. No. 12/181,409, the disclosures of which are totally incorporated herein by reference; and thereafter, applying to the aforementioned polyimide containing substrate a layer of a silane, such as an aminosilane, and which layer functions primarily as a primer layer that adheres the top layer to the silane layer and the supporting polyimide substrate layer of the member, and where the top layer is, for example, comprised of a crosslinked acrylic resin, a mixture of an aminoplast resin and an acrylic polyol resin, which mixture is crosslinked upon heating and where a catalyst can be selected to assist in the crosslinking; and a crosslinked mixture of a glycoluril resin and a self crosslinking acrylic resin. The intermediate transfer members disclosed herein in embodiments include a supporting substrate, such as a polyimide, which can be seamed or weldable (thermoplastic polyimide) or seamless (thermoset polyimide), and also the members may include a reverse double welded seam, where the seam is formed by ultrasonic welding on one side followed by ultrasonic welding on the opposite side.
Intermediate transfer belts can be generated in the form of seamed belts fabricated by fastening two ends of a web material together, such as by welding, sewing, wiring, stapling, or gluing. While seamless intermediate transfer belts are known, they may require manufacturing processes that render them more costly as compared to similar seamed intermediate transfer belts.
Seamed belts can be fabricated from a sheet cut that originates from an imaging member web. The sheets are generally rectangular, or in the shape of a parallelogram where the seam does not form a right angle to the parallel sides of the sheet. All edges may be of the same length, or one pair of parallel edges may be longer than the other pair of parallel edges. The sheets are formed into a belt by joining overlapping opposite marginal end regions of the sheet. A seam is typically produced in the overlapping marginal end regions at the point of joining. Joining of the aforementioned areas may be effected by any suitable means, such as by welding like ultrasonic welding, gluing, taping, pressure heat fusing, and the like.
Ultrasonic welding can be accomplished by retaining in a down position the overlapped ends of a flexible imaging member sheet with a vacuum against a flat anvil surface, and guiding the flat end of an ultrasonic vibrating horn transversely across the width of the sheet, over and along the length of the overlapped ends to form a welded seam. Ultrasonically welding results in an overlap seam that has an irregular surface topology rendering it difficult for a cleaning blade to remove toner around the seam, and such welding can also cause damage to the cleaning blades by nicking the cleaning edge of the blade. In addition, toner trapping resulting from the poor cleaning and the blade damage causes streaking from the seam and creates an image quality problem. Many post fabrication seam smoothing techniques, which remove material from the seam, may also degrade seam strength.
Also, when ultrasonically welded into a belt, the seam of a multilayered electrophotographic flexible imaging member may occasionally contain undesirable high protrusions such as peaks, ridges, spikes, and mounds. These seam protrusions present problems during image cycling of the belt because they interact with the cleaning blade causing blade wear and tear, which can affect cleaning blade efficiency and reduce service life.
In a typical electrostatographic reproducing apparatus, a light image of an original to be duplicated is recorded in the form of an electrostatic latent image upon a photosensitive member or photoconductor, and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles and colorant. Generally, the electrostatic latent image is contacted with a developer mixture comprised of carrier granules having toner particles adhering triboelectrically thereto, or a liquid developer material, which may include a liquid carrier having toner particles dispersed therein. The developer material is advanced into contact with the electrostatic latent image, and the toner particles are deposited thereon in image configuration. Subsequently, the developed image is transferred to a substrate like paper. It is advantageous to transfer the developed image to a coated intermediate transfer web, belt or component, and subsequently transfer with very high transfer efficiency the developed image from the intermediate transfer member to a permanent substrate. The toner image is subsequently usually fixed or fused upon a support, which may be the photoconductor or other support such as plain paper.
In electrostatographic printing machines, wherein the toner image is electrostatically transferred by a potential difference between the imaging member and the intermediate transfer member, the transfer of the toner particles to the intermediate transfer member, and the retention thereof should be substantially complete so that the image ultimately transferred to the image receiving substrate will have a high resolution. It is desired that substantially about 100 percent toner transfer occurs when most or all of the toner particles comprising the image are transferred, and little residual toner remains on the surface from which the image was transferred.
Intermediate transfer members in a xerographic environment allow for a number of advantages such as enabling high throughput at modest process speeds, registration of the final color toner image in color systems using synchronous development of one or more component colors using one or more transfer stations, and permitting a variety of final substrates that can be used. However, a bump, surface irregularity, or other discontinuity in the seam of the member, such as a belt, may disturb the tuck of the cleaning blade as it makes intimate contact with the photoconductive member surface to effect residual toner and debris removal. The increased height differential may allow toner to pass under the cleaning blade, and not be cleaned. Furthermore, seams having differential heights may, when subjected to repeated striking by cleaning blades, cause photoconductive member cycling speed disturbance which adversely affects the crucial photoconductive belt motion quality. Moreover, seams with a bump or any morphological defects can cause the untransferred residual toner to be trapped in the sites of the seam surface irregularities. The seam of a photoreceptor belt, which is repeatedly subjected to the striking action by a cleaning blade under machine functioning conditions, can trigger the development of premature seam delamination failure. In addition, the discontinuity in belt thickness due to the presence of an excessive seam height yields variances of mechanical strength in the belt, and reduces the fatigue flex life of the seam when cycling over belt module support rollers. As a result, both the cleaning life of the blade, and the overall service life of the photoreceptor belt can be diminished.
Moreover, the protrusion high spots in the intermediate member seam may also interfere with the operation of the xerographic subsystems by damaging electrode wires used in development, which wires parallel to and closely spaced from the outer imaging surface of a belt photoreceptor. These closely spaced wires are employed to facilitate the formation of a toner powder cloud at a development zone adjacent to a toner donor roll, and the imaging surface of the belt imaging member.
In operation, an intermediate transfer belt is contacted with a toner image bearing member such as a photoreceptor belt. In the contact zone, an electrostatic field generating device, such as a corotron, a bias transfer roller, a bias blade, or the like, creates electrostatic fields that transfer toner onto the intermediate transfer belt. Subsequently, the intermediate transfer belt is brought into contact with a receiver. An electrostatic field generating device then transfers toner from the intermediate transfer belt to the receiver. Depending on the system, a receiver can be another intermediate transfer member, or a substrate like paper onto which the toner will eventually be fixed.
Thus, there is a need for a seamed member, such as a belt, that avoids or eliminates a number of the disadvantages mentioned herein, and more specifically, there is a need for an intermediate transfer belt (ITB) where adhesion of the layers to each other are excellent, for example there is substantially no peeling of the layers. There also continues to be a need for an intermediate transfer member, such as a belt (ITB) with a coated seam or double welded seam surface topology such that it can withstand dynamic fatigue conditions; where the seam or seams are of minimum visibility and possess excellent surface resistivities; where, in embodiments, a reverse double welded seam can be achieved without additional finishing steps, such as sanding; and where the coating layer is mechanically robust and electrically matches the surface resistivity of the seamed ITB, and adheres strongly to the ITB base layer. For example, the coated seam as disclosed herein provides a smooth surface with substantially decreased or eliminated profile protrusions or irregularities thereby extending its service life. There is also a need for a substantially completely imageable seam, which avoids or minimizes the disadvantages indicated herein by overcoating the seam with a conducting polymer mixture layer, and which layer is mechanically robust and electrically matches the surface resistivity of the seamed intermediate transfer belt (ITB), or intermediate transfer member, which resistivity is, for example, from about 109 to about 1013 ohm/sq, and more specifically about 1010 ohm/sq.